Strong metal–support interactions (SMSI) is an important concept in heterogeneous catalysis. Herein, we demonstrate that the Au‐TiO2 SMSI of Au/TiO2 catalysts sensitively depends on both Au nanoparticle (NP) sizes and TiO2 facets. Au NPs of ca. 5 nm are more facile undergo Au‐TiO2 SMSI than those of ca. 2 nm, while TiO2 {001} and {100} facets are more facile than TiO2{101} facets. The resulting capsulating TiO2−x overlayers on Au NPs exhibit an average oxidation state between +3 and +4 and a Au‐to‐TiO2−x charge transfer, which, combined with calculations, determines the Ti:O ratio as ca. 6:11. Both TiO2−x overlayers and TiO2−x‐Au interface exhibit easier lattice oxygen activation and higher intrinsic activity in catalyzing low‐temperature CO oxidation than the starting Au‐TiO2 interface. These results advance fundamental understanding of SMSI and demonstrate engineering of metal NP size and oxide facet as an effective strategy to tune the SMSI for efficient catalysis.

Solid catalysts usually consist of multicomponents, within which interfacial interactions have been recognized as a key factor affecting structures and catalytic performance. Metal−support interactions (MSI) have been extensively studied in oxidesupported metal catalysts (metal/oxide catalysts), in which the important concepts of strong metal−support interactions (SMSI) and electronic metal−support interactions (EMSI) have been well established and their effects on the metal catalysis have been extensively demonstrated. Recently, metal-supported oxide inverse catalysts (oxide/metal inverse catalysts) have emerged as a new type of efficient catalysts, in which the oxide−metal interactions (OMI) strongly influence the oxide catalysis. Herein we comprehensively review the progresses on the MSI of metal/oxide catalysts and OMI of oxide/metal inverse catalysts with aims to emphasize structure sensitivity of MSI and OMI and to introduce the concepts of electronic oxide−metal interactions (EOMI) and electronic oxide−metal strong interactions (EOMSI) in oxide/metal inverse catalysts, in analogy to the concepts of EMSI and SMSI in metal/oxide catalysts. First, we briefly introduce the background of the topic and the interfacial interactions between metals and oxides with emphasis on the nature of metal−support interfacial interactions depending on the electronic structures. Second, the MSI, with an emphasis on the EMSI and SMSI, in metal/oxide catalysts is reviewed with an emphasis on the recently exported size and facet effects on the electronic structures and MSI. Third, the OMI in oxide/metal inverse catalysts is reviewed with an emphasis on introducing the EOMI and EOMSI. Finally, a summary and outlook is given with emphasis on the local nature and structure sensitivity of MSI and OMI.

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